Rafael Nadal wasn't clearly in a good mood after retiring in his US Open semi-final match against Juan Martin del Potro. The Spaniard was asked to compare his injuries with his biggest rivals, Novak Djokovic and Roger Federer.

'Sorry, but is not fair to compare myself with them,' Nadal said. 'Novak had something last year. Roger had couple of ones. But at the age of 36 is not the same. You can go to the history and you can compare how many Grand Slams I missed in my career, Masters 1000s, you can compare how many they missed.

Sorry, but is not the real comparation. But is part of the game. I can't and will not complain. Is just something that is like this. Even like this, I am in a good sport of the history of this sport, and keep going. That's all.

'I can't say that I am happy because I am not. I will not lie you. But, yes, he's a player that went through lot of issues during his career, like me too. I know how tough is this thing. I know how much frustration can be when you can't do the thing that you want to do.